1. Technical Field
The present invention relates to a piezoelectric device, a liquid ejecting head, and a liquid ejecting apparatus.
2. Related Art
A representative example of a liquid ejecting head that ejects liquid droplets includes an ink jet recording head that ejects ink droplets. As the ink jet recording head, for example, there is known a device that includes a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is formed, and a piezoelectric element disposed on one side of the flow path forming substrate, and in which ink droplets are ejected from the nozzle opening by causing a pressure change in ink in the pressure generating chamber by a piezoelectric element.
A wiring substrate is disposed so as to face the flow path forming substrate, and wiring disposed on the wiring substrate is connected to each of the piezoelectric elements. Specifically, the piezoelectric element includes an individual electrode individually disposed for each of active portions and a common electrode commonly disposed for a plurality of active portions, a driving signal is supplied to the individual electrode, and a bias voltage (vbs) is supplied to the common electrode (for example, refer to JP-A-2012-171149).
A core portion made of a resin material, and a bump wiring made of a plurality of wiring portions partially covering the core portion are disposed in the wiring substrate. The wiring portion on the wiring substrate side and the individual electrode and the common electrode of the piezoelectric element on the flow path forming substrate are connected to each other on the core portion. A plurality of such bump wirings are disposed for the individual electrode and for the common electrode.
However, one piezoelectric element row requires two bump wirings in total, the bump wiring for connecting the individual electrodes and the bump wiring for connecting the common electrodes. That is, a space for disposing at least two bump wirings is required for each piezoelectric element row, and thus a size of a liquid ejecting head is increased.
With a downsizing of the liquid ejecting head, the space for disposing the wiring for applying a bias voltage to the piezoelectric element row is restricted. Therefore, it is difficult to sufficiently secure a length and a cross-sectional area of the wiring and to lower an electric resistance, and thus there is a possibility that the bias voltage drops.
These problems are not limited to a piezoelectric device used in a liquid ejecting head such as an ink jet recording head, and are similarly present in the piezoelectric device used in another device.